Biologist Urmi explains what happens in our brain when we daydream
Many of us have made meditation a daily practice, striving to quiet the turmoil of thought, which haunts every moment. Can this be achieved? Can we bring our brain to rest at last? Could our identity be diluted in these moments? There is much to learn, but science already has some ideas about what happens when we meditate. First, it is necessary to discuss certain things about how the brain works.
Like the tip of an iceberg, the brain hides much more than what we see. We used to compare it to a computer, and imagine that when we stop carrying out a task the screen saver is activated and the brain goes to sleep to save energy. Nothing is further from the truth. In moments of relaxation, when we are lost in thought, mind wanderings or daydreaming, our brain becomes much more active. It has a hidden life much richer than we imagine.
Our brain is an insatiable devourer of energy, a black hole that consumes 20% of the calories we eat, although it represents no more than 2% of our body mass. Most of that energy is consumed when we are doing seemingly ‘nothing’. This means that making yourselves a coffee and reading this article uses less brain energy than wandering around in thought. Daydreaming consumes 20 times more energy, much more per gram than the beating of our heart.
The study of this energy expenditure led to the discovery by Marcus R. Raichle and Gordon L. Shulman in 2001, of the “default mode network of the brain (DMN),” also called the “neural dynamo of daydreaming.” A brain activity known long before, about which scientists thought was like the white noise of a television, always present in the background but useless. Now they think that DMN performs very important functions, by synchronizing the activity of various brain areas in the middle of the brain (medial prefrontal, medial parietal cortex and medial temporal lobes) any time we aren’t focused on a task.
Creating us, creating our world
The medial prefrontal cortex area of this default network is dedicated to evaluating things from a personal perspective, judging whether we consider something is good, bad or indifferent. Other areas are related to our identity and are activated when we ask people, for example, to choose from a list of adjectives which would apply to themselves, and which perhaps to John Travolta. That is, its function is to evaluate the internal image we have of ourselves in comparison to a standard or external model.
This default mode also has strong connections with the hippocampus – the memory center -, which recalls and brings “personal” memories to consciousness: how was your first day at school, or yesterday during an outburst of anger in the office, or your first kiss. During our daydreaming, the default network connects to the hippocampus to reach out and touch the deepest memories of our being: the material that shapes our dreams and obsessions. Later, the medial prefrontal cortex evaluates those memories from a self-referential viewpoint, which is the difference between remembering the fact that a hijacked plane crashed into the World Trade Center on September 11, and remembering where you were at the moment when you watched or heard about the attack. This network is responsible for an “inner rehearsal of your life”, during which the brain reflects on past experiences in order to weave seamlessly the personal narrative of our identity, and speculate about our future.
Wandering in thought is the intrinsic state of our brain and definitely plays a very serious role, as daily we accumulate mountains of short-term memories, of which only a few are worth keeping. The default network selects and stores these memories based on personal and emotional significance, to organize around them our identity and incorporate the lessons of the past into our future plan. All is done in a flurry of activity that diminishes or ceases as soon as we begin any particular task, whether reading, watching TV or meditating.
An Imagined Reality
Another of the curiosities in which this network may be involved, is in the construction of reality from the seemingly endless, but actually quite small, amount of information that reaches the brain from the outside. It is as if the data collected from the outside world by the senses passes through a bottleneck. So, from the ten billion bits per second of information that hits the retina, only 6 million bits per second pass through the optic nerve, due to its number of output connections. Of these only 10,000 bits per second reach the brain areas of vision, and of these only a few hundred play a role in creating a conscious perception. Researchers believe that there aren’t enough synapses to generate a perception that makes sense, and that the brain has to constantly make predictions about what happens on the outside from the data held inside from past experience, to complete the lack of external information. The default mode of the brain may be involved in this ongoing reconstruction of reality too.
At every moment we build reality based on predictions made on our past experiences and our current physiological state – for example, if we are hungry or not. It could be said that the reality in which we live is mainly the product of our inner life. What actually happens in the ‘now’ we barely perceive.
Always running behind the scene, the default network must sometimes give priority to the stimulus of the outside world. The smell of the food that burns in the kitchen, tells us that we must run to attend it. At such times the rich inner world of the default mode brain activity must be set aside to attend to more mundane priorities. However, this does not happen in people with depression, who are unable to completely disable the default system when they are doing other activities. They are incapable of getting lost in tasks, because the activity of those self-referential thoughts never cease. They are obsessed with an endless, vicious circle of what is happening to them.
Scientists have also seen that the normal pattern of the default network is also disturbed in Alzheimer’s disease, attention deficit disorder, depression, autism and schizophrenia, as well as vegetative coma patients. So, DMN seems to have a role in disorders in which conscious experience is altered or lost.
The inner world of meditation
Usually we say that meditation is the cessation of the constant flow of thought and the focus on the now, remaining aware from moment to moment. Although the brain never ceases its activity, we could say meditators are able to decrease the activity of the brain’s default mode – the wandering and brooding of self-referential thinking – specifically in those areas affected in patients of anxiety, attention deficit, depression and schizophrenia [Brewer et al (2011)]
In meditation we maintain a “focus attention” on the breath, the repetition of a specific phrase or other object of awareness, and we redirect our attention to this object when it has strayed. Then, what happens is exactly what will happen when we get lost in a task we love: the activities of the default mode network diminish. Because, remember, the DMN is active when we are not doing any focus oriented tasks!
Long-term meditators – those with more than 10,000 hours of “flight” -, are well trained to carry out their specific task, and have been reported to show greater attention span than average. Only in this type of meditator is it possible to observe a “permanent” variation of the brain structure due to repetition of the same task. This also happens with any other long-term type of expert, although different brain parts are affected depending on the activity they perform.
The training carried out by these meditators makes them able to simultaneously monitor what is going around and suppress the emergence of “I” thoughts, the urgency of dreaming and the mental dispersion, by decreasing the activity of the default system, mainly when they are meditating but also when they are not.
It would be too much to say that meditation is a cure for mental illness, although it could be a good palliative. These experiments suggest that there may be a neurological basis for the supposed benefits of meditation, in terms of increasing awareness, improving concentration and increasing the ability to deal with the emotional and mental stress of modern life.
Of course, a disproportionate effort to meditate could be counterproductive, in particular, if we are applying the same mental obsession that we use to achieve anything else. There is no difference. Our self-referential thinking might strive to create an image of what we would like to be, fighting against what we are in the domain of the DMN.
Is it possible to live without the functioning of this system, without the self-referential thought that creates a distance between us and the world? Perhaps. But science doesn’t know of anyone yet in which this network doesn’t operate, and for the time being, the “background noise” of our wandering mind is the intrinsic state of our brain.
Brewer, et al., “Meditation experience is associated with differences in default mode network activity and connectivity,” PNS, 2011 (108) 50: 20254-20259.
Raichle, Marcus E., “The Brain Dark Energy.” Scientific American, March 2010, pp. 44-49.
This article has been previously published in the German Osho Times, April 2012 issue: www.oshotimes.de
Urmi is Spanish, has a PhD in Biological Sciences and works as a journalist for the Spanish Television program ‘Redes’. She also writes for other media. She has been involved with the sannyas world since 1995. Meditation and science are her two main interests. Currently she teaches The Science of Conscious Leadership, a program she designed and developed for the University of Tarragona, Spain. She is also interested in Human Design and Ku Nye. She now lives in Cologne, Germany. Contact: urmisu (at) gmail.com